Soft deployment air bag fold

Abstract: A method of folding a vehicle occupant restraint air bag cushion (10) comprising the steps of: tucking a center of the cushion (10) towards a mouth (24) of the air bag to create two overlying pleats (30,32), rolling half of the bag into a roll (34), folding side portions between the pleats (30,32) to make the overall width of the bag (10) substantially the same as the width of an attachment retainer defining the mouth (24), rolling substantially the remainder of the bag (10) on to the roll (34), inserting the roll (34) into the retainer and folding an unrolled loop of the bag material over the roll which loop is arranged to form an upwardly projected bubble prior to downward unrolling of the bag upon bag deployment. The invention also covers a bag so folded.

Description: This invention relates to an air bag which is inflatable for restraining an occupant of a vehicle during a collision. More particularly, the invention relates to folding an air bag in a manner to improve the deployment thereof. Typically, an air bag cushion is folded and supported on the steering wheel or dashboard of a vehicle. When the air bag is to be inflated, high pressure gas from an inflator is caused to flow therein through a gas inlet opening or mouth thereof. This causes the air bag to unfold and inflate. Upon vehicle impact in a collision, top mounted air bag cushions, that is, those mounted near the top of the dashboard, tend to deploy high in the vehicle compartment and tend also to deploy with great velocity at the passenger's head. More specifically, as most air bag cushions deploy, the pressure in the cushion spikes to a high pressure initially. The high pressure ejects the folded cushion out of the air bag module with great velocity. This results in the cushion slapping the passenger as it unfolds. Such "slapping" of the passenger, particularly when an out-of-position child, with the cushion material could cause skin abrasions, excessive neck extension, and increase head injury criteria values. US Patent 5,290,061 (on which the pre-characterizing part of claim 1 is based) discloses a method for folding an air bag which involves first folding side portions of the bag inwardly then rolling all of the bag in a single operation towards a mouth of an inflator in which the roll of bag is accommodated prior to inflation. With this arrangement the bag can unroll away from the inflator completely before expansion of the bag in other directions occurs. Thus, there is a need and a demand for alleviating and/or correcting this problem so that the air bag cushion has a lower velocity deployment which results in elimination or reduction in "bag slap" injuries. An object of the invention is to provide an improved fold configuration for an air bag cushion that effects a reduction in the deployment velocity of the cushion and causes the cushion to deploy lower and more toward the vehicle occupant's midsection or torso. In order to cause the cushion to deploy lower and more toward the occupant's midsection, it must be folded in a manner such that it unfolds in along the rearward face of the dashboard. In order to reduce the velocity of the cushion deployment, the cushion must not unfold faster than the inflator can fill it with gas. To make the cushion deploy slowly in a downward trajectory, the cushion can have many stages of different types of folds which can only unfold in sequence one after another. Air bag cushion folds known in the prior art use a folded "bubble" on top, tucks, a pleat and rolls which inversely unroll down the instrument panel of the dashboard. The present invention uses several of such folds in sequence. According to the present invention there is provided a folded inflatable air bag cushion of air bag fabric and having a mouth for restraining a vehicle occupant, said air bag cushion being adapted to be top mounted on a dashboard of the vehicle and using several fold variations including at least some of: a folded bubble on top, tucks, a pleat and at least one roll which is adapted to inversely roll down the dashboard of the vehicle when an inflating fluid flows into the cushion, characterised in that the fold variations comprise: a. a tuck of a center of the cushion towards the mouth creating opposed pleats, b. a first roll of the pleats rolled towards the mouth creating opposed pleats, c. folds of side portions of the bag situated between the pleats, and d. a further roll including at least a majority of the remainder of the bag rolled onto the first roll, which folds are such that they can only unfold in a reverse of the sequence a to d and that said air bag cushion does not unfold faster than it can be filled with inflating fluid and deploys relatively slowly in a downward trajectory. As the cushion deployment develops, pressurized gas stored therein pushes open each fold one after another until the cushion fully deploys. If the folds of the cushion are diffucult for the inflator pressurized gas to push open, this reduces the velocity of the cushion as it unfolds. With the present invention, a bubble of fabric first opens against the windshield of the vehicle, pushing the seat of the cushion fold downward. Next, a roll of fabric unfolds downward against the instrument panel and then fabric portions tucked into each side of the unrolled cushion are pushed out. This allows the next roll to unfold along the instrument panel. Finally, the center of the fabric blossoms out allowing the cushion to fill completely with gas. The effectiveness of the air bag cushion fold configuration of the present invention in solving the problem of high velocity deployment which increases "bag slap" injuries to vehicle occupants is demonstrated by comparing its pressure-time curve with that of other air bag cushion folds. As most cushion folds deploy, the pressure in the cushion spikes initially to a high pressure. This high pressure ejects the folded cushion out of the module with great velocity. This great velocity causes the pressure in the cushion to go negative, that is, become less than zero, because the cushion begins to unfold faster than the inflator can supply gas to fill it up. As the air bag cushion fold configuration of the present invention deploys, however, the pressure in the cushion does not usually go negative because the fold sequence does not allow the cushion to eject with a velocity great enough to cause this to happen. According to a second aspect of the invention there is provided a method for folding an air bag cushion according to the first aspect of the invention. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the specification. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. With this description of the invention, a detailed description follows with reference being made to the accompanying drawings which form part of the specificiation, of which: Fig. 1 is a schematic illustration portraying partial inflation of an air bag cushion which had been folded and stored in a manner known in the prior art to restrain a passenger in a vehicle during a collision; Fig. 2 is a depiction, in various stages of development, of an air bag cushion that had been folded and stored in the vehicle in accordance with the present invention and includes a depiction of the cushion at full bag deployment and pressure; Fig. 3A and 3B are plan and side views, respectively, of the air bag cushion of Figs. 1 and 2 lying flat prior to folding; Fig. 4 is a plan view of the air bag cushion of Figs. 2, 3A and 3B unfolded and uninflated and laid flat so that the bottom of the cushion faces up, with a portion of the center of the cushion tucked in toward the cushion gas inlet or mouth, creating an upper and a lower pleat; Fig. 5 is a side view of the Fig. 4 cushion showing the upper and lower pleats; Figs. 6 and 7 are views similar to Figs. 4 and 5, respectively, but showing the lower cushion pleat partially rolled with the upper pleat, stopping after about half of the fabric is rolled up; Figs. 8 and 9 are views similar to Figs. 6 and 7 but showing one side of the rolled cushion fabric tucked in between the upper and lower pleats; Fig. 10 is a view similar to Fig. 9 but showing the side of the cushion with tucked in fabric; Fig. 11 is a plan view similar to Fig. 8 but showing the rolled cushion fabric on the opposite side of the air bag cushion tucked inside the bag between the upper and lower pleats; Fig. 12 is an inverted view of Fig. 11 showing the tucked in cushion fabric on the opposite side; Fig. 13 is a plan view similar to Fig. 11 but showing additional rolling of the bag toward the mouth of the cushion; Fig. 14 is a side view showing the upper and lower pleats of the folded cushion of Fig. 13; Fig. 15 is a plan view similar to Fig. 11 showing the roll inserted into the mouth of the cushion retainer leaving a loop of excess fabric protruding; Fig. 16 is a side view of the rolled up cushion shown in Fig. 15; Fig. 17 is a plan view similar to Fig. 15 showing the excess fabric rolled over the roll; and Fig. 18 is a side view of the rolled up cushion shown in Fig. 17. In inflatable air bag systems for restraining a passenger of a vehicle during a collision, a folded air bag cushion commonly is stored in a module mounted high on the dashboard of the vehicle. Upon the occurrence of a collision of the vehicle, the folded air bag cushion is inflated to restrain the passenger. Initiation of inflation of a folded air bag cushion 10 known in the prior art to restrain a passenger in a vehicle is illustrated in Fig. 1. As shown in Fig. 1, a pressurized fluid such as nitrogen gas produced by an inflator (not shown) is forced to flow into the mouth of the cushion to cause a portion of the cushion to deploy at great velocity initially toward the head 12 of a passenger 14 of the vehicle. Initial deployment of a folded air bag cushion 10 having the same construction as the air bag cushion 10 shown in Fig. 1 is illusrated in Fig. 2. The air bag cushion 10 in Fig. 2, however, is folded in accordance with the present invention. As the pressurized nitrogen gas or other inflating fluid enters the air bag cushion 10 shown in Fig. 2, a portion of the cushion initially deploys toward the midsection of the passenger 14 in the vehicle. Initially, in Fig. 2, the inflating air bag cushion 10 does not deploy toward the head 12 of the passenger 16, as in the prior art arrangement illustrated in Fig. 1. When in a fully inflated condition, the air bag cushions 10 of Figs. 1 and 2 are positioned between the passenger 14 and the dashboard 20 and windshield 16 of the vehicle and restrain movement of the passenger 14 during sudden deceleration of the vehicle. The air bag cushion 10 illustrated in Figs. 3A and 3B is lying flat prior to folding. As shown, the air bag cushion 10 includes a generally rectangular attachment or retainer 26 that defines the inflating gas inlet opening or mouth 24 of the cushion 10 and connects the air bag cushion 10 to the dashboard of the vehicle. The air bag cushion fold according to the invention is illustrated in Figs. 4 through 18 of the drawings and comprises Steps 1 through 7, as described hereinafter. Step 1: As shown in Fig. 4, lay the cushion 10 so that the bottom 27 of the cushion 10 faces up. Tuck the center 28 of the cushion toward the cushion mouth 24 thereby creating an upper pleat 30 and a lower pleat 32, as shown in Fig. 5. The pleats 30 and 32 should be even in length or the upper pleat 30 may be longer than the lower pleat 32. Step 2: As shown in Figs. 6 and 7, roll the lower pleat 32 with the upper pleat 30 to form a roll 34 stopping after about half of the fabric is rolled up. If the upper pleat 30 is longer than the lower pleat 32, as shown in Figs. 4 and 5, roll the upper pleat 30 first and then include the lower pleat 32 in the roll 34 when it is met. Step 3: Tuck one side of the rolled cushion fabric in between the upper pleat 30 and the lower pleat 32, as illustrated in Figs. 8, 9 and 10. Step 4: Tuck the opposite side of the rolled cushion fabric between the upper pleat 30 and the lower pleat 32, as illustrated in Figs. 11 and 12. At this point in the folding operation, the width of the folded cushion 10 should be about the width of the mouth 24 of the cushion. Step 5: As shown in Figs. 13 and 14, continue rolling the fabric of the air bag cushion toward the mouth 24 of the cushion to form a roll 36, stopping at a point where Steps 6 and 7 may be performed. Step 6: As shown in Figs. 15 and 16, insert the roll 36 as folded to this point into the mouth 24 of the cushion retainer 26 leaving a loop 38 of excess fabric protruding. Step 7: Fold over excess fabric 38 over the roll 36 as shown in Figs. 17 and 18. As those skilled in the art will understand, the foregoing steps according to the invention could achieve the same effect in other orders and by repeating the same steps during the folding process. Upon inflation of the air bag cushion 10 folded in accordance with the invention and mounted in the dashboard 20 of a vehicle, a bubble 40 formed by the loop 38 of excess fabric first opens against the windshield, as shown in Fig. 2. This causes the rest of the cushion fold to be pushed downward. The roll of fabric 36 then unfolds downward against the dashboard, following which the fabric portions tucked into each side of the unrolled cushion are pushed out. This allows the next roll 34 to unfold. The center of the fabric finally blossoms out allowing the cushion to completely fill with gas. This unfolding of the folded air bag cushion 10 is along the rearward face of the dashboard 20 of the vehicle. Because the cushion has many stages of different types of folds which can only unfold in sequence one after another, the cushion deploys relatively slowly in a downward trajectory, with initial deployment of the cushion 10 against the midsection of the passenger 14. The velocity of cushion deployment is reduced because the cushion can not unfold faster than the inflator can fill it with gas. With this description of the invention in detail, those skilled in the art will appreciate that modifications may be made to the invention without departing from the spirit thereof. Therefore, it is not intended that the scope of the invention be limited to the specific embodiment that has been illustrated and described. Rather, it is intended that the scope of the invention be determined by the scope of the appended claims.

Claims: A folded inflatable air bag cushion (10) of air bag fabric and having a mouth (24) for restraining a vehicle occupant, said air bag cushion (10) being adapted to be top mounted on a dashboard (20) of the vehicle and using several fold variations including at least some of: a folded bubble (38,40) on top, tucks, a pleat (30,32) and at least one roll (34,36) which is adapted to inversely roll down the dashboard (20) of the vehicle when an inflating fluid flows into the cushion (10), characterised in that the fold variations comprise: a. a tuck of a center (28) of the cushion (10) towards the mouth (24) creating overlying pleats (30,32), b. a first roll (34) of the pleats (30,32) rolled towards the mouth (24) and including less than all of the bag (10), c. folds of side portions of the bag (10) situated between the pleats (30,32), and d. a further roll (36) including at least a majority of the remainder of the bag (10) rolled onto the first roll (34), which folds are such that they can only unfold in a reverse of the sequence a to d and that said air bag cushion (10) does not unfold faster than it can be filled with inflating fluid and deploys relatively slowly in a downward trajectory. The air bag cushion (10) as claimed in claim 1 wherein the first roll (34) includes about half of the fabric of the air bag cushion. The air bag cushion (10) as claimed in claim 1 or 2 wherein the side portion folds are such as to make the width of the folded cushion substantially the same as the width of the mouth (24). The air bag cushion (10) as claimed in any preceding claim wherein the further roll (36) is inserted into the mouth (24). The air bag cushion (10) as claimed in any preceding claim wherein a loop (38) of excess air bag fabric is folded over the further roll (36). The air bag cushion (10) as claimed in any preceding claim wherein one pleat (30) is longer than the other pleat (32) and the first roll (34) includes a roll of the longer pleat (30) alone followed by a roll of the two pleats (30,32) where the pleats overlie. A method of folding an inflatable air bag cushion (10) of air bag fabric and having a mouth (24) comprising the following steps with the cushion initially in an uninflated state and unfolded: a. tucking the center (28) of the cushion (10) towards the mouth (24) creating overlying pleats (30,32), b. rolling the pleats together towards the mouth (24) to form a first roll (34) including less than all of the bag (10), c. folding side portions of the bag (10) between the pleats (30,32), and d. rolling at least a majority of the remainder of the bag (10) onto the roll (34) to form a further roll (36). The method claimed in claim 7 wherein step b is stopped after about half of the air bag fabric has been rolled onto the first roll (34). The method claimed in claim 7 or 8 wherein at the conclusion of step c the width of the folded cushion is substantially the same as the width of the mouth (24). The method claimed in claim 7, 8 or 9 wherein the further roll (36) is inserted into the mouth (24). The method claimed in any one claims 7 to 10 wherein after step d a loop (38) of excess fabric is folded over the rolled cushion. The method claimed in claim 11 wherein the loop (38) is deployable upon initial inflation of the air bag (10) to form an upwardly deployable bubble (40) prior to downward unrolling of the rolled air bag (10). The method claimed in any one of claims 7 to 12 wherein one pleat (30) is longer than the other pleat and (32) rolling of the longer pleat (30) is effected followed by inclusion of the other pleat (32) when it is met.

Inventors: DYER DAVID J, PAXTON DONALD J, DYER, DAVID J., PAXTON, DONALD J.
Applicants: MORTON INT INC, MORTON INTERNATIONAL, INC.
Application year: 1994
Main classification: B60R21
IPC codes: B60R21